Engine pinging
08-31-2018, 01:16 PM
#1
Instructor
Thread Starter
Engine pinging
Howdy
ive seen some posts about engine pinging detonation but there doesn’t seem to be any definitive cause. Nobody has figured out what causes it on a stock motor/tune?
my only mod is knn cai. The plug wires are on securely. 2008 z06 with 40k miles.
The car pings under load and upper range rpm. It surges at lower rpm when cold. Wasn’t throwing any codes or check engine light till today when I took it to redline. The engine bogged down and check eng light came on. It starts and idles fine.
My dealership says it might be carbon build up from not using top tier fuel and 91 octane - which is all I have access to.
Thoughts??
ive seen some posts about engine pinging detonation but there doesn’t seem to be any definitive cause. Nobody has figured out what causes it on a stock motor/tune?
my only mod is knn cai. The plug wires are on securely. 2008 z06 with 40k miles.
The car pings under load and upper range rpm. It surges at lower rpm when cold. Wasn’t throwing any codes or check engine light till today when I took it to redline. The engine bogged down and check eng light came on. It starts and idles fine.
My dealership says it might be carbon build up from not using top tier fuel and 91 octane - which is all I have access to.
Thoughts??
08-31-2018, 01:35 PM
#2
Team Owner
Careful...detonation is no joke on these cars. Crack a sleeve or break a ring land on a piston under load with detonation. Hard to say, but if you truly are bone stock...build up may be it. I would be doing a seafoam treatment to try and clean the top end, and then replace the plugs (and maybe wires too).
08-31-2018, 02:40 PM
#3
Well - CEL doesnt come on from knock sensors so you have another issue on your hands. Scan it and check it out before driving more.
As for detonation - a bone stock LS7 will knock right out of the factory. They run the timing very high in the stock tune once you add the high octane, afr spark, and iat tables up.
The car is calibrated for 93 in perfect conditions.
Also - many tests have shown the stock spark plug to be too hot and cause knock. Many run the TR6 to avoid that.
As for detonation - a bone stock LS7 will knock right out of the factory. They run the timing very high in the stock tune once you add the high octane, afr spark, and iat tables up.
The car is calibrated for 93 in perfect conditions.
Also - many tests have shown the stock spark plug to be too hot and cause knock. Many run the TR6 to avoid that.
Last edited by Apocolipse; 08-31-2018 at 02:41 PM.
08-31-2018, 03:01 PM
#4
Melting Slicks
Add a can of BG 44K Fuel System Cleaner 208 to a tank of gas and see if that helps.
08-31-2018, 03:26 PM
#5
Instructor
Thread Starter
This just started within the past couple of months, never heard it before I’ve had the car since 2011.
Chevy told me not to add fuel cleaners but did suggest octane booster.
Chevy told me not to add fuel cleaners but did suggest octane booster.
08-31-2018, 06:29 PM
#6
The problem with carbon build up is the ECM can't retard the spark to cancel it out. The carbon glows and lights off the air fuel mixture before the spark plug fires. Sorta like a diesel effect
08-31-2018, 08:31 PM
#8
Team Owner
You could pull some plugs and bore scope the piston tops.
09-01-2018, 01:55 PM
#12
Le Mans Master
Could also be oil in the intake manifold. Oil aerosol is only 40 octane...so mix that with 91, and you could rapidly develop a nasty knock. I recommend checking plugs (look for wetness or other signs of shenanigans) and pull the CAI and TB off to look in the intake for oil. Knock will definitely kill cylinders if you let it happen. Do NOT, I repeat do NOTTTTTTTT keep your foot in it if you hear knock. By then it's usually too late. Report back when you have some findings. I also think you should add some Torco or Race fuel concentrate. This will tell you if it's octane related.
09-01-2018, 05:42 PM
#13
Team Owner
Cylinder 7 is typically the leanest (intake manifold design), and where a lot of liner and ring land failures occur. I would be bore scoping that piston for sure...certainly not driving it anymore until I did.
09-01-2018, 05:47 PM
#14
You're just throwing darts blindly if you don't have scanning software like HP Tuners. If you want to diagnose the issue, get HP tuners and log your car and you'll get all the data you need to diagnose and fix your problems.
09-05-2018, 06:34 PM
#18
Instructor
Thread Starter
So they replaced the coil pack and I can’t duplicate the pinging under load or the engine bog near redline. Seems to have done the trick. Hello 6900 rpm! 
That said I’ll ask a few questions related to everyone’s thoughts/advice which I very much appreciate:
1. Doesn’t carbon build up on all engines?
2. Why aftermarket plugs vs factory? Is there really any hard data that shows a difference?
3. Where do you buy those plugs cuz I can’t find any local?
4. Suggestions for aftermarket plug wires vs stock ones? And are aftermarket wires justified with any hard data?
That said I’ll ask a few questions related to everyone’s thoughts/advice which I very much appreciate:
1. Doesn’t carbon build up on all engines?
2. Why aftermarket plugs vs factory? Is there really any hard data that shows a difference?
3. Where do you buy those plugs cuz I can’t find any local?
4. Suggestions for aftermarket plug wires vs stock ones? And are aftermarket wires justified with any hard data?
09-05-2018, 07:28 PM
#19
Racer
So they replaced the coil pack and I can’t duplicate the pinging under load or the engine bog near redline. Seems to have done the trick. Hello 6900 rpm!
That said I’ll ask a few questions related to everyone’s thoughts/advice which I very much appreciate:
1. Doesn’t carbon build up on all engines?
2. Why aftermarket plugs vs factory? Is there really any hard data that shows a difference?
3. Where do you buy those plugs cuz I can’t find any local?
4. Suggestions for aftermarket plug wires vs stock ones? And are aftermarket wires justified with any hard data?
That said I’ll ask a few questions related to everyone’s thoughts/advice which I very much appreciate:
1. Doesn’t carbon build up on all engines?
2. Why aftermarket plugs vs factory? Is there really any hard data that shows a difference?
3. Where do you buy those plugs cuz I can’t find any local?
4. Suggestions for aftermarket plug wires vs stock ones? And are aftermarket wires justified with any hard data?
2. The combination of things like very warm climates, poor fuel quality, high cylinder pressure/temperature (compression, boost, nitrous) can benefit from using a lower heat range and/or non-projected tip plug to reduce pre-ignition.
3. They are EVERYWHERE. Most common LS plug, 1 heat range cooler, non-projected is the NGK TR6 plug
4. Aftermarket wires provide no gains. Reducing plug wire resistance from 650 ohms down to 50 ohms by using a MSD wire instead of factory AC Delco, provides no gain. The resistance across your spark plug gap is likely in the MEGAOHMS range. Saving a few hundred ohms wont do ****. Buy a nice set of factory AC Delco wires off Amazon for $30. Done.
Last edited by roastin300; 09-05-2018 at 07:31 PM.
